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Lee, Youngkyun,Hyung, Seok-Won,Jung, Hee Jung,Kim, Hyung-Joon,Staerk, Judith,Constantinescu, Stefan N.,Chang, Eun-Ju,Lee, Zang Hee,Lee, Sang-Won,Kim, Hong-Hee American Society of Hematology 2008 Blood Vol.111 No.2
<P>Interferons (IFNs) have been shown to negatively regulate osteoclastogenesis. In a proteomic study to assess protein expression during osteoclastogenesis, we discovered that the expression level of Jak1 was significantly decreased during the early stage of osteoclast differentiation from mouse bone marrow macrophages (BMMs) upon stimulation with receptor activator of nuclear factor κB ligand (RANKL). RANKL induced Jak1 ubiquitination, and a proteasome inhibitor MG132 efficiently blocked the RANKL-induced degradation of Jak1. The expression level of Jak1 correlated with the susceptibility of osteoclast precursors to the negative regulatory effects of IFN-β on osteoclastogenesis, since preosteoclasts (pOCs) in which Jak1 expression is significantly reduced could proceed with osteoclastogenesis in the presence of IFN-β. Forced down-regulation of Jak1 by small interfering RNA (siRNA) resulted in the efficient osteoclast differentiation of BMMs in the presence of inhibitory IFN-β, while overexpression of Jak1 in pOCs elicited IFN-β-dependent inhibition of osteoclastogenesis. Furthermore, we found that the IFN-β-induced inhibition of osteoclastogenesis required STAT3 downstream of Jak1. These data suggest that the regulation of Jak1 expression during osteoclast differentiation might serve as an intrinsic mechanism that determines osteoclast lineage commitment by modulating the negative regulation by IFN-β.</P>
Eui-Seon Lee,Tae-Young Kim,Yam Prasad Aryal,Kihyun Kim,Seongsoo Byun,Dongju Song,Yejin Shin,Dany Lee,Jooheon Lee,Gilyoung Jung,Seunghoon Chi,Yoolim Choi,Youngkyun Lee,Chang-Hyeon An,Jae-Young Kim 대한구강생물학회 2021 International Journal of Oral Biology Vol.46 No.2
This study summarizes the recent cutting-edge approaches for dentin regeneration that still do not offer adequate solutions. Tertiary dentin is formed when odontoblasts are directly affected by various stimuli. Recent preclinical studies have reported that stimulation of the Wnt/β-catenin signaling pathway could facilitate the formation of reparative dentin and thereby aid in the structural and functional development of the tertiary dentin. A range of signaling pathways, including the Wnt/β-catenin pathway, is activated when dental tissues are damaged and the pulp is exposed. The application of small molecules for dentin regeneration has been suggested as a drug repositioning approach. This study reviews the role of Wnt signaling in tooth formation, particularly dentin formation and dentin regeneration. In addition, the application of the drug repositioning strategy to facilitate the development of new drugs for dentin regeneration has been discussed in this study.
Lee, Ji-Eun,Bark, Chung Wung,Quy, Hoang Van,Seo, Seung-Jun,Lim, Jae-Hong,Kang, Sung-A,Lee, Youngkyun,Lee, Jae-Mok,Suh, Jo-Young,Kim, Yong-Gun MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.11
<P>The regeneration of bone defects caused by periodontal disease or trauma is an important goal. Porous hydroxyapatite (HA) is an osteoconductive graft material. However, the hydrophobic properties of HA can be a disadvantage in the initial healing process. HA can be coated with TiO<SUB>2</SUB> to improve its hydrophilicity, and ultraviolet irradiation (UV) can further increase the hydrophilicity by photofunctionalization. This study was designed to evaluate the effect of 5% TiO<SUB>2</SUB>-coated HA on rabbit calvarial defects and compare it with that of photofunctionalization on new bone in the early stage. The following four study groups were established, negative control, HA, TiO<SUB>2</SUB>-coated HA, and TiO<SUB>2</SUB>-coated HA with UV. The animals were sacrificed and the defects were assessed by radiography as well as histologic and histomorphometric analyses. At 2 and 8 weeks postoperatively, the TiO<SUB>2</SUB>-coated HA with UV group and TiO<SUB>2</SUB>-coated HA group showed significantly higher percentages of new bone than the control group (<I>p</I> < 0.05). UV irradiation increased the extent of new bone formation, and there was a significant difference between the TiO<SUB>2</SUB>-coated HA group and TiO<SUB>2</SUB>-coated HA with UV group. The combination of TiO<SUB>2</SUB>/HA and UV irradiation in bone regeneration appears to induce a favorable response.</P>
Lee, Ji-Eun,Lee, Jae-Mok,Lee, Youngkyun,Park, Jin-Woo,Suh, Jo-Young,Um, Heung-Sik,Kim, Yong-Gun Korean Academy of Periodontology 2017 Journal of Periodontal & Implant Science Vol.47 No.3
Purpose: This study aimed to evaluate the effects of a cetylpyridinium chloride (CPC) and tranexamic acid (TXA) mouth rinse on patients with gingivitis. Methods: This randomized, placebo-controlled, double-blind, parallel-group, clinical trial included 45 healthy adults with gingivitis, who were randomized into 2 groups. The experimental group used a 0.05% CPC and 0.05% TXA mouth rinse, and the control group used a placebo mouth rinse. The following clinical indices were assessed at baseline, at 3 weeks, and at 6 weeks: the Turesky-Quigley-Hein plaque index (QHI), the $L{\ddot{o}}e-Silness$ gingival index (GI), and bleeding on marginal probing (BOMP). The subjects used the mouth rinse during the experimental period for 20 seconds, 4-5 times daily (10 mL each time). Results: There were no significant differences in the clinical indices between the groups at baseline. In the experimental group (CPC+TXA), a statistically significant improvement was evident in the QHI, GI, and BOMP at 3 and 6 weeks. These results were similar to those observed in the control group at 3 and 6 weeks, although the change in BOMP was not statistically significant in that group. At 6 weeks, the experimental group had a significantly lower mean score for the QHI than the control group. Conclusions: This study demonstrated that a CPC and TXA mouth rinse exhibited significant antiplaque and anti-gingivitis efficacy, and had a positive effect on bleeding control when used daily for 6 weeks.
Characteristics of low-<i>κ</i> SiOC films deposited via atomic layer deposition
Lee, Jaemin,Jang, Woochool,Kim, Hyunjung,Shin, Seokyoon,Kweon, Youngkyun,Lee, Kunyoung,Jeon, Hyeongtag Elsevier S.A. 2018 Thin Solid Films Vol.645 No.-
<P><B>Abstract</B></P> <P>The deposition of SiOC thin films via remote plasma atomic layer deposition was investigated. Octamethylcyclotetrasiloxane (OMCTS) and O<SUB>2</SUB>, Ar, H<SUB>2</SUB> plasmas were respectively used as a precursor and reactants during the deposition process at 400°C. Plasma and deposition temperatures had a significant effect on the physical and electrical characteristics of the films. When Ar and H<SUB>2</SUB> plasma was respectively used during the deposition process, films exhibited low dielectric constants while incorporating carbon; however, O<SUB>2</SUB> plasma yielded carbon free SiO<SUB>2</SUB> films. Low dielectric constants resulted in low film densities and the presence of carbon within the films. When Ar and H<SUB>2</SUB> plasma was used as the reactant gas, pores within the films with loose structures and SiC bonds served to lower the dielectric constant. As a result, Ar and H<SUB>2</SUB> plasma conditions exhibited low dielectric constants of 2.7 and 3.1 at 100°C, respectively. Meanwhile, the presence of carbon and low film densities caused leakage paths within the films. X-ray photoelectron spectroscopy supported analyses demonstrating the bonding characteristics of Si, C, O components.</P> <P><B>Highlight</B></P> <P> <UL> <LI> SiOC thin films prepared by atomic layer deposition (ALD) with O<SUB>2</SUB>, Ar, H<SUB>2</SUB> plasma. </LI> <LI> O<SUB>2</SUB> plasma is unfavorable to incorporate carbon into SiOC films. </LI> <LI> SiOC ALD deposited with Ar plasma showed low k but high leakage property. </LI> <LI> H<SUB>2</SUB> plasma made SiOC ALD thin films with low k and low leakage property. </LI> </UL> </P>
Lee, Youngkyun,Kim, Hyung Joon,Park, Cheol Kyu,Kim, Woo-Shin,Lee, Zang Hee,Kim, Hong-Hee Mary Ann Liebert, Inc 2012 Journal of bone and mineral research Vol.27 No.5
<P>Osteoclasts are bone-resorbing cells differentiated from macrophage/monocyte lineage precursors upon receptor activator of NF-관B ligand (RANKL) stimulation. In a proteomic approach to identify proteins involved in osteoclastogenesis, we observed a dramatic increase in the expression of neurite outgrowth inhibitor A (Nogo-A) upon RANKL stimulation of mouse bone marrow macrophages (BMMs) in a nuclear factor of activated T cell cytoplasmic 1 (NFATc1)-dependent manner. The knockdown of Nogo-A in BMMs significantly reduced RANKL-dependent osteoclast differentiation accompanied by diminished NFATc1 induction, suggesting that a positive feedback mechanism is involved. Conversely, Nogo-A overexpression in BMMs as well as in RAW264.7 macrophages greatly augmented osteoclastogenesis, with concomitant increase in the NFATc1 induction. Both the mitogen-activated protein kinase (MAPK) pathway and calcium oscillation, which are central to RANKL-dependent NFATc1 activation and induction, were enhanced by Nogo-A. Finally, Nogo-A knockdown in mouse calvariae prevented interleukin 1 (IL-1)-induced bone loss. These findings not only reveal an unprecedented extraneural role of Nogo-A in osteoclastogenesis but also suggest a novel drug target against bone-lytic diseases.</P>
Economic evaluation of pressurized LNG supply chain
Lee, Sanghyuk,Seo, Youngkyun,Lee, Jaemin,Chang, Daejun Elsevier 2016 Journal of natural gas science and engineering Vol.33 No.-
<P><B>Abstract</B></P> <P>This study developed a high-level conceptual design of a Pressurized Liquefied Natural Gas (PLNG) supply chain with marine production, transportation, and utilization steps and estimated the life cycle cost (LCC) of the chain to assess its economic feasibility. The PLNG supply chain consisted of a Floating Liquefied Natural Gas Unit (FLNG) and a LNG Shuttle-and-Regasification Vessel (SRV). Because PLNG was produced, stored, and transported at a higher temperature and pressure than ambient-pressure LNG (ALNG), the PLNG supply chain reduced production (liquefaction) and regasification costs while increasing storage and shipping costs relative to those for ALNG, mainly due to the requirement for heavy containment systems to carry the PLNG. To reduce PLNG storage and shipping costs by improving the volume efficiency of the pressure containment system, a novel concept for a prismatic pressure vessel was employed for the pressure cargo tanks. An assessment of economic feasibility estimated the normalized LCC for a range of product pressures and shipping distances. The assessment showed that PLNG was economically feasible when the PLNG pressure was 5 bar and at short shipping distances. The cost of the pressure containment system proved to be the critical cost component. A sensitivity study demonstrated that a decrease in the material cost for the containment system could significantly increase the breakeven shipping distance. Under optimum conditions, the cost for transporting PLNG was 6% less than that of transporting ALNG.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new supply chain for PLNG transporting consisted of the FLNG and SRV is proposed. </LI> <LI> Suggested supply chain employs the novel prismatic pressure tanks. </LI> <LI> The PLNG supply chain is economical for short shipping distances when the storage tank is constructed with 9% Ni. </LI> <LI> When High Mn is used for the tanks, the PLNG supply chain becomes more economical than that of ALNG at longer distances. </LI> </UL> </P>
Slow relaxation of randomly packed hard spheres
Lee, Jongjin,Lee, Changwon,Yu, Insuk,Jung, Youngkyun,Lee, Jysoo IOP Pub 2007 Journal of Physics, Condensed Matter Vol.19 No.35
<P>We discover that the apparent weight and the electrical resistance of randomly packed stainless steel balls exhibit unusually slow relaxation behavior. It is found experimentally that these relaxations are due to structural change of the packing. Simultaneous measurements of the apparent weight and the electrical resistance show correlated time dependence. We have also performed two-dimensional molecular dynamics simulations and studied a possible mechanism for the slow relaxation behavior observed in experiments.</P>